The present invention is related to a vibration generator of a vibrating plate compactor for compacting road surfaces, and more particularly to a bearing lubrication system of a vibration generator wherein lubricating oil stored inside may be supplied efficiently to the bearings of an eccentric rotor shaft.
A bearing lubrication system provided in the vibration generator for the vibrating plate compactor is known from such prior art as U.S. Pat. Nos. 3,782,845, 4,113,403, and 5,220,845 wherein the oil in an oil-bath type housing is stirred by vibrations caused by rotation of the eccentric rotor axially attached in a freely rotatable fashion inside the housing and turned into mists by diffusion caused by rotational wind pressure. The oil mist then attaches to the bearings of the rotor shaft exposed inside the housing and lubricates the shaft to facilitate rotation.
The oil mist attaches to the inner wall of the center chamber in the housing along the rotational direction of the eccentric rotor, flows toward bearings on the left and the right, and attaches to the inner edges of the bearings exposed on both sides of the center chamber inside the housing, thereby lubricating the bearings.
As mentioned above, the oil mist generating with rotation of the eccentric rotor in the housing in the conventional vibration generator attaches to the inner edges of the left and the right bearings exposed on both sides of the center chamber in the housing and lubricates the respective bearings, but the center chamber is not connected by a passage to the left and the right outer chambers and the bearings of the rotor shaft.
Therefore, the oil mist generated in the center chamber of the housing merely attaches to the inner edges of bearings exposed on both sides, does not flow toward the left and right outer chambers in the housing, and only an insufficient amount of the oil mist attaches to the outer edges of bearings in the outer chamber, thereby causing a state of insufficient lubrication.
The oil mist in the housing center chamber attaches to the inner edges of bearings exposed on both sides and enters the space between the ball rotating surface of the inner race and the outer race and that of the ball and the ball retainer. As the inner race and the balls are rotating at a high speed, the amount of oil mist flowing in the direction of the outer edge through the bearing is very much restricted.
With the amount of oil mist flowing in the direction of the outer edges through the bearing thus restricted, the inner edges of bearings inside the center chamber may be sufficiently lubricated, but not the outer edges of the same bearings in the outer chambers, thus generating high heat due to insufficient lubrication.
As a part of the bearing becomes very hot due to insufficient lubrication, the oil in the center chamber also becomes hot due to the heat of the bearing and the oil film required for lubrication decreases, causing wear by metallic friction to the bearings and eventually resulting in damage.
The present invention was contrived in view of the problems mentioned above in the oil lubricating system for a conventional vibration generator of a vibrating plate compactor. Rotation of an eccentric rotor is utilized to supply the oil not only to the housing center chamber but also to the outer chambers on the left and the right of bearings of the rotor shaft. The present invention therefore aims to impart optimum lubrication by supplying the oil to the inner and the outer edges of bearings and to extend their durability.
As a means to embody the present invention, an oil lubricating system of a vibration generator for lubricating the shaft of the eccentric rotor by diffusing the oil in the housing by rotating the eccentric rotor is provided with a rotor shaft supported by bearings in a freely rotatable fashion at both ends thereof in the housing, a center chamber and outer chambers partitioned by said bearings, and an oil supply passage along the axial direction on the left and the right shafts axially mounted on the bearings to let the oil in the center chamber flow toward the outer chambers.
According to a preferred embodiment of the present invention, said oil supply passage is so constructed that the top surface is below the centerline of the rotor shaft when the eccentric rotor is stationary, and the rotor shafts positioned at both ends of this top surface are provided with a hollow hole opened along the centerline of the rotor shaft.
Said oil supply passages should preferably be cone shaped with a smaller inner diameter on the center chamber side and the larger inner diameter on the outer chamber side. of the two oil supply passages in said rotor shaft, the passage provided on the rotor shaft on the side of a pulley to which the power is transmitted from outside is closed at its outer end by a closure means, but the portion inside the passage in front of the closure means and the outer chambers in the housing is open.
When providing an opening between the point in front of the closure means in the oil supply passage of the rotor shaft on the pulley side and the outer chamber in the housing, the opening should preferably be cone shaped with a larger inner diameter on the oil supply passage side and a smaller inner diameter on the outer chamber side.
According to another preferred embodiment of the present invention, the connecting part between the eccentric rotor and the rotor shaft is reinforced by parallel reinforcement walls connecting the inner edges of a rotor shaft and of another rotor shaft on the side of the top surface along the rotor shaft centerline when the eccentric rotor is stationary.
The oil lubrication system of vibration generator according to the present invention is provided with a center the housing, the outer chambers being partitioned by the left and the right bearings, and oil supply passages along the axial direction to let the oil in the center chamber flow toward the outer chambers. The oil diffused in the center chamber by rotation of the eccentric rotor not only lubricates the inside of the bearings in the center chamber but also flows into the outer chambers after passing through the oil supply passages on both sides of the rotor shaft from the top surface of the eccentric rotor to lubricate the outside of said bearings from the outer chambers. As a result, uneven lubrication of the bearings as in the prior art is corrected, and well-balanced lubrication of the center chamber and the outer chambers is facilitated, to thereby extend the durable life of the vibration generator.